University of Groningen
Prevailing head position to one side in early infancy - a population-based study
Straathof, Elisabeth J M; Heineman, Kirsten R; Hamer, Elisa G; Hadders-Algra, Mijna
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Acta Paediatrica
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10.1111/apa.15112
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Straathof, E. J. M., Heineman, K. R., Hamer, E. G., & Hadders-Algra, M. (2020). Prevailing head position to
one side in early infancy - a population-based study. Acta Paediatrica, 109(7), 1423-1429.
https://doi.org/10.1111/apa.15112
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1 | INTRODUCTION
Head control is one of the prerequisites for young infants to learn and explore their environment.1 In early infancy, proper head control
is not yet fully established, reflecting that development needs time. In the first month after birth, head movements may be considered as an element of non–object-oriented exploratory behaviour, that is head movements against gravity and towards the midline or to the Received: 10 September 2019
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Revised: 25 November 2019|
Accepted: 26 November 2019DOI: 10.1111/apa.15112 R E G U L A R A R T I C L E
Prevailing head position to one side in early infancy—A
population-based study
Elisabeth J. M. Straathof
1| Kirsten R. Heineman
1,2| Elisa G. Hamer
1,3|
Mijna Hadders-Algra
1This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
© 2019 The Authors. Acta Paediatrica published by John Wiley & Sons Ltd on behalf of Foundation Acta Paediatrica
Abbreviations: CA, corrected age; IMP, Infant Motor Profile; METc, Medical Ethical Committee; OR, odds ratio; PHP, prevailing head position to one side; SINDA, Standardized Infant
NeuroDevelopmental Assessment; SPSS, Statistical Package for the Social Sciences; UMCG, University Medical Center Groningen.
1University of Groningen, Department of
Paediatrics - Division of Developmental Neurology, University Medical Center Groningen, Groningen, The Netherlands
2Stichting Epilepsie Instellingen Nederland
(SEIN), Zwolle, The Netherlands
3Radboud University Medical Center,
Department of Neurology, Nijmegen, The Netherlands
Correspondence
Mijna Hadders-Algra, Developmental Neurology, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands. Email: m.hadders-algra@umcg.nl
Funding information
The study was supported by the CorneliaStichting and the Stichting Ontwikkelingsneurofysiologie Groningen.
Abstract
Aim: To determine the prevalence of prevailing head position to one side (PHP) in young infants and to evaluate its associations with reaching performance, neurologi-cal condition and perinatal and socio-economic factors.
Methods: Observational study in 500 infants (273 boys) 2-6 months corrected age, representative of the Dutch population (median gestational age 39.7 weeks (27-42); birthweight 3438 g (1120-4950). Prevailing head position to one side and reaching performance were assessed with the Infant Motor Profile; neurological condition with the Standardized Infant NeuroDevelopmental Assessment. Socio-economic information and perinatal information were obtained by questionnaire and medical records. Associations were analysed with uni- and multivariable statistics.
Results: Prevailing head position to one side was observed in 100 infants (20%), and its prevalence decreased from 49% at 2 months to 0% at 6 months. Only in infants aged 4-5 months PHP was significantly associated with worse reaching and an at-risk neurological score. Prevailing head position to one side was weakly associated with prenatal substance exposure, post-natal admission to a paediatric ward and paternal native Dutch background.
Conclusion: Prevailing head position to one side at 2-3 months is a frequently occur-ring sign with limited clinical significance. Yet, PHP at 4-5 months is associated with a worse functional and neurological condition. Therefore, PHP at 4-5 months could serve as a red flag indicating possible challenges in later development.
K E Y W O R D S
infancy, motor development, neurological condition, perinatal risk, prevailing head position [Correction added on 21 January 2020, after
first online publication: Author affiliations have been updated in this current version.]
2
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STRAATHOF eTAl.contralateral side. This exploratory behaviour allows infants to learn to control their bodies.2 This, in turn, is essential for the
develop-ment of early behaviours in which vision and movedevelop-ments of trunk and arms are involved, such as reaching and grasping—behaviours that are largely dependent on adequate postural control.3-5 Impaired
head control is regarded as a manifestation of neurological non-op-timality. Therefore, items evaluating head behaviour are included in all common infant neurological assessment methods.6-8
A frequently occurring clinical manifestation of non-optimal head control is a prevailing head position to one side (PHP).9 The prevalence
of PHP increased after the launch of the Back to Sleep campaign by the American Academy of Pediatrics in 1994, rising to 10%-11% in infants aged 2-4 months in the Netherlands in 2001.10,11 PHP may lead to
de-formational plagiocephaly, a condition that has been associated with developmental delays in gross and fine motor function, problem-solv-ing and personal social skills.12-14 Although the studies reporting these
associations have several limitations and only show tentative results, they do state that PHP could be a marker of conditions impeding typi-cal development, such as neuromuscular conditions and environmental positioning limitations.15 Professional awareness of these associations
and caregivers' concerns about the asymmetric motor behaviour of the infant frequently results in referral to paediatric physiotherapy.10
Knowledge about the current prevalence of PHP in the gen-eral population is sparse. The data available are Dutch data of in-fants aged 2-6 months of the general population in 1995,10 data of
4-month-olds in the general New Zealand population in 200416 and
data of 2-3 months old term born infants from the Netherlands and Italy, studied in 200517 and 2015,18 respectively. In addition, no data
are available on PHP's association with functional abilities, such as reaching, and with perinatal risk factors. The IMP-SINDA project offered an excellent opportunity to fill this knowledge gap. In the IMP-SINDA project, we collected norm data for two novel infant assessments: the Infant Motor Profile (IMP)19 and the Standardized
Infant NeuroDevelopmental Assessment (SINDA)7 in a large
sam-ple representative of the Dutch population. The current study fo-cussed on infants aged 2-6 months. In these infants, we addressed the following questions: (a) What is the prevalence of PHP?; (b) Is PHP associated with worse performance in reaching, grasping and manipulation?; (c) Is PHP associated with an impaired neurological condition in general, and—more specifically—with impaired postural control reflected by an atypical performance during the pull-to-sit manoeuvre?; and (d) Is PHP associated with perinatal and socio-eco-nomic risk factors?
2 | PATIENTS AND METHODS
2.1 | Study population
In this cross-sectional study, we evaluated motor behaviour of 500 infants (273 boys and 227 girls) aged 2-6 months corrected age (CA). The infants were the youngest infants of the IMP-SINDA project. Inclusion criteria of the IMP-SINDA project were as follows: age
2-18 months CA living in the northern part of the Netherlands (cov-ering about a quarter of the surface area of the Netherlands) and having caregivers with sufficient comprehension of the Dutch lan-guage. Infants were only excluded if they were too ill to be assessed (eg severe congenital heart disease with insufficient oxygen satu-ration). We achieved the aim to recruit 100 infants per age month, whose socio-economic background is representative of the general Dutch population. Recruitment took place at well-baby clinics and by advertisements. Each infant was assessed once. The infant's age in a specific age month category ranged from 2 weeks prior to the exact age in months CA to 2 weeks after that exact age, for example the age of 3 months CA ranged from 2 months and 15 days to 3 months and 14 days. The Medical Ethical Committee of the University Medical Centre Groningen (UMCG) approved the study design (ap-proval number: METc 2016/294). All caregivers provided written informed consent.
2.2 | Procedures
Infants were assessed between January 2017 and March 2019 at the Institute of Developmental Neurology of the UMCG, at well-baby clinics or at the infant's home, depending on caregivers' prefer-ences. A team of trained assessors examined the infants. The entire assessment was video-recorded. The videos served two goals: (a) enabling the assessors to perform the IMP-assessment, which is a video-based assessment; and (b) serving as a means for supervision of the SINDA. The assessors were supervised by two experts (MHA and KRH for the IMP; MHA for the SINDA), who were not aware of the socio-economic background and clinical history of the infant. The experts are reliable assessors of the IMP and SINDA; the good reliability of their performances was reported elsewhere.7,19
2.3 | Measurements
2.3.1 | Perinatal and socio-economic characteristics
Caregivers filled out a standardised questionnaire on prenatal, peri-natal and neoperi-natal (in short: periperi-natal) and socio-economic history.Key notes
• In the general Dutch population, the prevalence of pre-vailing head position (PHP) steeply decreases from 49% at 2 months to 0% at 6 months.
• PHP at 2-3 months has limited clinical significance, but PHP at 4-5 months is associated with worse functional and neurological condition.
• PHP in the general population is only weakly associated with perinatal risk factors.
If the questionnaire revealed complications, medical records were consulted. Based on these data, a perinatal risk score was calculated (Table 1).
2.3.2 | Infant Motor Profile
Prevailing head position to one side was determined on the basis of the IMP, a valid and reliable video-based assessment of self-produced motor behaviour in different positions in infants aged 3-18 months. Its 80 items provide information on the domains vari-ation, adaptability, symmetry, fluency and motor performance.19
The IMP includes three items on PHP, that is items evaluate the presence of asymmetrical head position in supine, prone and (sup-ported) sitting position. These IMP items are scored as no or mildly/ moderately/strongly PHP. Prevailing head position to one side was defined as the presence of a moderately or strongly prevailing head position in at least two of the three positions mentioned above. The infant's ability to reach, grasp and manipulate was based on the IMP-performance item assessing this ability when the infant sits on the caregiver's lap (score range 1-7; a higher score denotes a better per-formance; Table 2).
2.3.3 | SINDA's neurological scale
The SINDA is a novel neurodevelopmental screening instrument ap-plicable for infants aged 6 weeks to 12 months. SINDA's neurological scale consists of 28 items, scored as typical or atypical. It results in a score ranging from 0 to 28, with 28 indicating best performance. A total score of ≤ 21 (the at-risk neurological score) was associated with an increased risk of a developmental disorder.7 One of the items
evaluates the infant's behaviour during the pull-to-sit manoeuvre. Atypical performance implies the presence of head lag, active head retroflection and/or insufficient hip flexion. The first study on SINDA's neurological scale indicated that it is a reliable and valid as-sessment tool.7
2.4 | Statistical analysis
To calculate the study's power a two-sample t test for the reaching parameter was performed, assuming that the overall prevalence of PHP at 2-6 months was 6%.10 Considering a 1-point difference in the
reaching score as clinically relevant, the sample size of 500 results in a power of 80% (α = .05).
Associations between PHP on the one hand and reaching be-haviour and SINDA's total neurological score on the other were evaluated with the Mann-Whitney U test; those between PHP and an at-risk neurological score and atypical pull-to-sit manoeuvre with the chi-square test, with Phi as the measure of the effect size. Associations between PHP and perinatal risk factors were assessed with the chi-square test and the Mann-Whitney U test. Next, we
performed backward multivariable logistic regression analysis to de-termine which factors contributed most to PHP; only factors that reached P < .15 in the univariable analyses were entered into this analysis. Throughout the analyses, confidence intervals (CI) were set at 95%, and P-values < .05 were considered statistically signifi-cant (two-tailed). In case of missing data on perinatal characteristics, cases were omitted from the association analyses. Statistical analy-ses were performed using Statistical Package for the Social Sciences (SPSS), version 23 (SPSS IC., Chicago, IL).
3 | RESULTS
The background characteristics of the study group are shown in Table 1. They reflect the low-risk nature of the group with a me-dian gestational age of 39.7 weeks (range 27-42) and a meme-dian birth-weight of 3438 g (range 1120-4950). The study group contained two infants with a known syndrome: one was diagnosed with trisomy 21 and one with Gorlin syndrome. The background characteristics re-semble those of the general Dutch population, including the preva-lence of preterm birth (6.2% in our study and 6.8% in the general population)20 and the infants' socio-economic background
(preva-lence of highly educated mothers 40% in our study and 37% in the general population).21
3.1 | Prevalence of PHP
The prevalence of PHP in our total study group was 20%, with a steady and significant decrease from 49% at 2 months to 0% at 6 months (Table 2, Figure 1A).
3.2 | PHP and performance on reaching,
grasping and manipulation
Prevailing head position to one side was significantly associated with worse reaching, grasping and manipulation (in short: reaching; P < .001; Table 2). This association was age dependent (Figure 1B): only infants aged 4-5 months with PHP scored significantly lower on reaching than their peers without PHP (P < .001).
3.3 | SINDA's neurological scale scores and PHP
SINDA's neurological scores ranged from 11 to 28 points, with a median value of 25. This reflects the low-risk nature of the study group. Prevailing head position to one side was associated with a significantly lower SINDA neurological score; this held true for all ages (Figure 1C). Fifty-five infants of the total group (11%) had an at-risk neurological score. Also, the at-risk score was associated with PHP (P < .001). The association was age dependent. In the infants aged 2-3 months, the at-risk score was not associated with PHP4
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STRAATHOF eTAl.(at-risk score in infants with PHP: 18/81 (22%); in infants without PHP 16/119 (13%)) (χ2(1) = 2.631, Phi = 0.115, P = .105). However, in
infants aged 4-5 months the at-risk score was associated with PHP (at-risk score in infants with PHP: 6/19 (32%); in infants without PHP: 10/181 (6%); χ2(1) = 15.859, Phi = 0.282, P < .001). An
atypi-cal performance on the pull-to-sit manoeuvre was present in 172 infants (34%). It was clearly associated with PHP (χ2(1) = 33.318,
Phi = 0.258, P < .001). This association was not age dependent.
3.4 | Perinatal risk factors and PHP
Univariable analyses revealed that PHP was significantly associated with prenatal substance exposure (χ2(1) = 5.015, Phi = 0.100, P = .025),
post-natal admission to the neonatal ward (χ2(1) = 4.611, Phi = 0.096,
P = .032), jaundice requiring phototherapy (χ2(1) = 7.087, Phi = 0.119,
P = .008), a lower paternal occupation level (U = 15 569, P = .022), and TA B L E 1 Socio-economic and perinatal characteristics
Sex (boy/girl), n (%) 273 (55)/227 (45)
Maternal education level*,a
I/II/III/IV, n (%) 10 (2)/53 (11)/234
(47)/202 (40)
Paternal education level*,a
I/II/III/IV, n (%) 18 (4)/42 (9)/228 (48)/189
(40)
Maternal occupation level*,b
I/II/III/IV, n (%) 110 (22)/121 (24)/116
(23)/150 (30)
Paternal occupation level*,b
I/II/III/IV, n (%) 63 (13)/190 (40)/92 (19)/130 (27) Maternal age in years, mean ± SD 29.9 ± 4.7 <20/20-34/≥35, n (%) 2 (0.4)/416 (83)/82 (16) Paternal age* in years, mean ± SD 32.9 ± 6.3 <20/20-39/≥40 0/427 (88)/57 (12)
Maternal ethnicityc: native
Dutch/non-native Dutch, n (%)
447 (89)/53 (11)
Paternal ethnicity*,c: native
Dutch/non-native Dutch, n (%)
440 (90)/48 (10) Pre-pregnancy maternal BMI*
in kg/m2, median (range) 24.1 (17.2-48.4) <25/25-29/≥30, n (%) 285 (57)/134 (27)/79 (16) Assisted reproduction*, n (%) 36 (7) hormonal treatment, n (%) 11 (2) intrauterine insemination, n (%) 15 (3) IVF/ICSI, n (%) 10 (2) Maternal smoking*, n (%) 53 (11)
Prenatal substance exposure (alcohol and/or drugs)*, n (%) 5 (1) Maternal medication*,d, n (%) 58 (12) Diabetes*, n (%) 37 (7) without medication, n (%) 18 (4) with medication, n (%) 19 (4) Hypertension*, n (%) 68 (14) without medication, n (%) 49 (10) with medication, n (%) 19 (4) Thyroid disease*, n (%) 15 (3) without medication, n (%) 3 (0.6) with medication, n (%) 12 (2) Instrumental delivery, n (%) 123 (25) caesarean section, n (%) 85 (17)
vacuum or forceps extraction, n (%) 38 (8)
Gestational age
in weeks, median (range) 39.7 (27.3-42.1)
(Continues)
preterm/term, n (%) 31 (6)/469 (94)
Birthweight
in grams, median (range) 3438 (1120-4950)
SGA (<P10)/APA (P10-90)/LGA
(≥P90), n (%) 60 (12)/384 (77)/56 (11)
Twin, n (%) 12 (2)
Meconium in amniotic fluid*, n (%) 73 (15)
Non-optimal start*,e, n (%) 43 (9)
Admission to neonatal ward, n (%) 101 (20)
Jaundice requiring phototherapy,
n (%) 21 (4)
Perinatal risk score*, median (range) 2 (0-7)
Note: Bold: factors included in the perinatal risk score and their criteria; score range 0-23; a higher score denotes a higher risk; at the bottom of the table.
aI = no or only primary education/II = primary or secondary vocational
education and training/III = secondary vocational training, senior general secondary education and university preparatory education/ IV = vocational college and university.
bBased on the International Standard Classification of Occupations,
ISCO.28 I = ISCO1 and unemployed/II = ISCO2/III = ISCO3/IV = ISCO4.
cNative Dutch: location of birth is the Netherlands. Non-native Dutch:
location of birth is not the Netherlands.
dUsed one of the following: insulin; antihypertensive medication;
thyroid-stimulating medication; antidepressants/antipsychotics/ benzodiazepines; anti-epileptic medication.
eThe presence of delayed onset of crying, respiratory difficulties
requiring monitoring on the neonatal ward and/or respiratory intervention, short-lasting floppiness or cyanosis.
*Missing: maternal education level n = 1; paternal education level n = 23; maternal occupation level n = 3; paternal occupation level n = 25; paternal age n = 16; paternal ethnicity n = 12; maternal BMI n = 2; [pregnancy characteristics n = 1;] assisted reproduction n = 4; maternal smoking, prenatal substance exposure, maternal medication, diabetes, hypertension, thyroid disease n = 1; meconium in amniotic fluid n = 2; non-optimal start, admission to neonatal ward, jaundice requiring phototherapy n = 1; perinatal risk score n = 34.
paternal native Dutch background (χ2(1) = 6.098, Phi = 0.112, P = .014).
The perinatal risk score was not associated with PHP (P = .748). Multivariable logistic regression analysis indicated that prenatal sub-stance exposure (OR = 10.08, 95% CI 1.02-99.77), post-natal admission to neonatal ward (OR = 1.72, 95% CI 1.02-2.91) and paternal native Dutch background (OR = 3.89, 95% CI 1.18-12.86), explained PHP best. Note that these variables together only explained 5.3% of the variance. The infant's age did not play a role.
4 | DISCUSSION
In our low-risk study group, 20% of infants showed PHP, with a prevalence that decreased from 49% at 2 months to 0% at 6 months. Prevailing head position to one side in infants aged 2-3 months was not related to reaching nor to an at-risk neurological score. However, in infants aged 4-5 months PHP was associated with less optimal reaching and an at-risk neurological condition. Perinatal factors were only weakly associated with PHP.
The prevalence of PHP at 4 months in our study (16%) is some-what higher than the 11% previously reported in a large study group of infants younger than 6 months assessed in 1995 that was rela-tively representative of the Dutch population.10 The different
fig-ures could imply that the prevalence of PHP in young infancy has increased during the last two decades. However, Hutchison and colleagues who studied PHP in a cohort of 200 infants—being qual-ified by the presence of plagiocephaly and brachycephaly—in New Zealand in 2004, reported a PHP prevalence at 4 months of 19.7%.16
This would argue against an evident increase over the years. Most likely, the different prevalence percentages reported in the studies may be attributed to the differences in criteria for PHP and cultural differences in infant handling and positioning. The data do not allow for a conclusion on the effect of culture on PHP over time.
Our data indicated that PHP in infants aged 2-3 months was not associated with reaching performance and neurological condition, whereas in infants aged 4-5 months it was. It is conceivable that this age-related difference is brought about by the major transition in the brain occurring at this time. Around 3 months of age the primary TA B L E 2 Neuromotor performance from 2 to 6 mo
Neuromotor behaviour
Age in months
2 (n = 100) 3 (n = 100) 4 (n = 100) 5 (n = 100) 6 (n = 100) Total (n = 500)
PHPa, n (%) 49 (49) 32 (32) 16 (16) 3 (3) 0 (0) 100 (20)
Reaching, grasping and manipulationb, n (%)
1. No prereaching or reaching 44 17 3 0 0 64 (13) 2. No reaching, but prereaching 48 56 39 12 0 155 (31)
3. Reaching, but no grasping 7 22 15 7 1 52 (10)
4. Reaching, grasp-ing and holdgrasp-ing but no manipulation
1 4 7 5 0 17 (3)
5. Reaching, holding and manipulation of 1 object
0 1 27 40 19 87 (17)
6. Reaching, holding and manipulation of 2 objects
0 0 9 35 79 123 (25)
7. Reaching, holding and manipulation of ≥3 objects
0 0 0 1 1 2 (0.4)
SINDA
Neurological scorec, median
(25-75th percentile) 24 (22-26) 25 (23-26) 25 (23.25-27) 25 (24-26) 25 (24-26) 25 (23-26)
At-risk neurological score (≤ 21), n (%)
20 (20) 14 (14) 9 (9) 7 (7) 5 (5) 55 (11)
Atypical pull-to-sit
manoeu-vred, n (%) 71(71) 46 (46) 26 (26) 17 (17) 12 (12) 172 (34)
Note: Associations between PHP and (a) reaching, grasping and manipulation: U = 7750.5, P < .001; (b) SINDA neurological score: U = 13 013.5, P < .001; (c) SINDA at-risk neurological score: χ2(1) = 21.478, Phi = 0.207, P < .001; (d) atypical pull-to-sit manoeuvre: χ2(1) = 33.318, Phi = 0.258,
P < .001.
aPrevalence decreased with increasing age: H(4) = 105, r = −.45, P < .001.
bScore increased with increasing age: r
s = .818, P < .001.
cScore increased with increasing age: r
s = .212, P < .001.
6
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STRAATHOF eTAl.sensory and motor cortices no longer involve the temporary struc-ture of the subplate; from that age onwards, they only rely on the permanent circuitries of the cortical plate.22 This developmental
change is accompanied by a transition in the infant's behaviour: the general movements are in their final phase and are getting re-placed by goal-directed behaviour.23,24 Simultaneously the infant
has achieved the ability to balance the head.25 Proper head balance
is one of the prerequisites for goal-directed reaching.3,5
Interestingly, having a non-native Dutch father was associated with a lower risk of PHP, which supports the suggestion that eth-nic background and cultural habits may play a role in the genesis of PHP.18,26 PHP was only associated with two perinatal risk factors:
prenatal substance exposure and post-natal admission to the neona-tal ward. The latter suggests that PHP is associated with an impaired capacity to cope with the transition from intra- to extrauterine life, which in turn corresponds to the less optimal neurological condition of infants with PHP (Figure 1). In contrast to other reports,10,17 we
did not find an association between PHP and preterm birth and male sex. The reason that we did not find an association with preterm birth could be that in our sample, that was representative of the Dutch population, only a few children had been born very preterm. Especially infants who have been born very preterm have an in-creased risk of PHP. For instance, Nuysink et al27 reported that the
prevalence of PHP at 3 months CA in infants born before 30 weeks gestational age was 37% and that of deformational plagiocephaly 50%. Similar to PHP in term infants, PHP in very preterm infants mostly has a favourable prognosis.
A major strength of our study is the relatively large group of well-documented infants that—despite being recruited in the north-ern parts of the Netherlands—is representative of the general Dutch population in terms of perinatal and demographic characteristics. This
supports the generalisability of the study's findings to the general population of Dutch infants aged 2-6 months. An additional strength is the use of two standardised assessments—the IMP and SINDA—to evaluate PHP, reaching and neurological condition. It may be consid-ered a limitation that we performed the IMP in infants aged 2 months, whereas the IMP has been designed for infants aged 3-18 months. Two-month-olds were included to facilitate the calculation of norm curves. It turned out that the IMP could be well assessed in all 1.5- to 2.5-month-old infants. Another limitation is the absence of informa-tion on daily life activities, such as posiinforma-tioning during sleeping, feeding and playing, as these activities may have acted as effect mediators.17
5 | CONCLUSION
We found a 20% overall prevalence of PHP in young infants. Our study confirms that PHP in young infants is largely age dependent. In our representative Dutch sample, it had a high prevalence at 2 months and it had disappeared at 6 months, suggesting that it is a transient form of neurological non-optimality. Prevailing head position to one side was only weakly associated with perinatal risk factors. Prevailing head position to one side at 2-3 months had a high prevalence and was not associated with reaching and an at-risk neurological condition. This indicates that PHP at 2-3 months has limited clinical significance. Yet, PHP at 4-5 months was associated with worse reaching skills and with an at-risk neurological condition. The latter may imply PHP in infants aged 4-5 months may serve as a red flag indicating possible challenges for later development. We therefore suggest the following: (a) when the infant does not show clear neurological dysfunction accompany-ing PHP, caregivers may be reassured by receivaccompany-ing information on the transient nature of PHP; yet, caregivers also need to be informed that F I G U R E 1 Prevalence of PHP, scores on reaching performance and SINDA's neurological scale. (A) Prevalence of PHP at various ages. Panels B and C: Bold horizontal lines indicate median values, boxes present 25th and 75th centiles, vertical lines indicate ranges, and outliers are represented by dots or asterisks. (B) Box plot of IMP-scores on reaching, grasping and manipulation in infants with and without PHP at the various ages. The large black dot at 6 mo indicates that the vast majority of infants obtained score 6, implying that they could hold and manipulate two objects (infants 2-3 mo: difference between infants with and without PHP: Mann-Whitney, P = .107; infants 4-5 mo: difference between infants with and without PHP: Mann-Whitney, P < .001). (C) SINDA's neurological scale scores in infants with and without PHP at the various ages (difference between infants with and without PHP: Mann-Whitney, P < .001)
6 5 4 3 2 100 80 60 40 20 0 % 6 5 4 3 2
SINDA neurological score
28 27 26 25 24 23 22 21 20 19 18 17 16 15 12 11 PHPno PHP 6 5 4 3 2
IMP score on reaching, grasping
and manipulation 7 6 5 4 3 2 1 PHP no PHP PHP
age in months (CA) age in months (CA) age in months (CA)
when PHP persists until 4-5 months, physiotherapeutic intervention is warranted; (b) that health professionals provide caregivers of all young infants with PHP with information on how they can promote the in-fant's ability to achieve symmetric head positioning and symmetric and varied head movements in all directions, how they can promote the in-fant's head balancing abilities and how they can encourage the inin-fant's reaching and grasping activities; and (c) that 4- to 5-month-old infants with PHP receive physiotherapeutic intervention.
ACKNOWLEDGEMENTS
We thank all infants and parents who participated in the IMP-SINDA project. We acknowledge the assistance of the medical students and the research assistants of the Kinderacademie Groningen in data collection. We also gratefully acknowledge the technical assistance of Anneke Kracht-Tilman.
CONFLIC T OF INTEREST
The authors have stated that they had no interests that might be perceived as posing a conflict or bias.
ORCID
Elisabeth J. M. Straathof https://orcid. org/0000-0001-8591-4642
Kirsten R. Heineman https://orcid.org/0000-0002-9566-2132 Mijna Hadders-Algra https://orcid.org/0000-0001-6845-5114 REFERENCES
1. Lee H., Galloway J.C. Early intensive postural and movement training advances head control in very young infants. Phys Ther. 2012;92:935-947.
2. Babik I., Galloway J.C., Lobo M.A. Infants born preterm demon-strate impaired exploration of their bodies and surfaces throughout the first 2 years of life. Phys Ther. 2017;97:915-925.
3. Thelen E., Spencer J.P. Postural control during reaching in young infants: a dynamic systems approach. Neurosci Biobehav Rev. 1998;22:507-514.
4. Bertenthal B., Von Hofsten C. Eye, head and trunk control: the foundation for manual development. Neurosci Biobehav Rev. 1998;22:515-520.
5. Hadders-Algra M. Typical and atypical development of reaching and postural control in infancy. Dev Med Child Neurol. 2013;55:5-8. 6. Dubowitz L., Dubowitz V., Mercuri E. The Neurological Assessment of
the Preterm & Full-term Newborn Infant. 2nd revised ed. London, UK: Mac Keith Press; 2011.
7. Hadders-Algra M., Tacke U., Pietz J., Rupp A., Philippi H. Reliability and predictive validity of the Standardized Infant NeuroDevelopmental Assessment neurological scale. Dev Med Child Neurol. 2019;61:654-660.
8. Amiel-Tison C., Gosseling J. Neurological Development from Birth to Six Years: Guide for Examination and Evaluation. Baltimore, MD: The Johns Hopkins University Press; 2001.
9. Van Vlimmeren L.A., van der Graaf Y., Boere-Boonekamp M.M., L'Hoir M.P., Helders P.J., Engelbert R.H. Effect of pediatric physical therapy on deformational plagiocephaly in children with positional preference: a randomized controlled trial. Arch Pediatr Adolesc Med. 2008;162:712-718.
10. Boere-Boonekamp M.M., van der Linden-Kuiper L.T. Positional preference: prevalence in infants and follow-up after two years. Pediatrics. 2001;107:339-343.
11. Koren A., Reece S.M., Kahn-D'angelo L., Medeiros D. Parental infor-mation and behaviors and provider practices related to tummy time and back to sleep. J Pediatr Health Care. 2010;24:222-230. 12. De Bock F., Braun V., Renz-Polster H. Deformational plagiocephaly
in normal infants: a systematic review of causes and hypotheses. Arch Dis Child. 2017;102:535-542.
13. Martiniuk ALC, Vujovich-Dunn C., Park M., Yu W., Lucas B.R. Plagiocephaly and developmental delay: a systematic review. J Dev Behav Pediatr. 2017;38:67-78.
14. Hutchison B.L., Steward A.W., de Chalain T., Mitchell E.A. Serial de-velopmental assessments in infants with deformational plagioceph-aly. J Paediatr Child Health. 2012;48:247-278.
15. Collett B., Breiger D., King D., Cunningham M., Speltz M. Neurodevelopmental implications of ‘deformational’ plagiocephaly. J Dev Behav Pediatr. 2005;26:379-389.
16. Hutchison B.L., Hutchison L.A., Thompson J.M., Mitchell E.A. Plagiocephaly and brachycephaly in the first two years of life: a prospective cohort study. Pediatrics. 2004;114:970-980.
17. Van Vlimmeren L.A., van der Graaf Y., Boere-Boonekamp M.M., L'Hoir M.P., Helders P.J., Engelbert R.H. Risk factors for deforma-tional plagiocephaly at birth and at 7 weeks of age: a prospective cohort study. Pediatrics. 2007;119:e408-e418.
18. Ballardini E., Sisti M., Basaglia N., et al. Prevalence and characteris-tics of positional plagiocephaly in healthy full-term infants at 8–12 weeks of life. Eur J Pediatr. 2018;177:1547-1554.
19. Heineman K.R., Bos A.F., Hadders-Algra M. The Infant Motor Profile: a standardized and qualitative method to assess motor be-haviour in infancy. Dev Med Child Neurol. 2008;50:275-282. 20. Perined. Perinatale Zorg in Nederland 2016. Utrecht, Netherlands:
Perined; 2018.
21. Centraal Bureau voor de Statistiek. Bevolking; onderwijsniveau; geslacht, leeftijd en migratieachtergrond [Internet]. https ://opend ata. cbs.nl/statl ine/#/CBS/nl/datas et/82275 NED/table ?froms tatweb. Accessed July 1, 2019.
22. Hadders-Algra M. Early human brain development: starring the subplate. Neurosci Biobehav Rev. 2018;92:276-290.
23. Prechtl H.F.R., Nolte R. Motor behaviour of preterm infants. In: Prechtl HFR, ed. Continuity of Neural Functions from Prenatal to Postnatal Life. Oxford, UK: Blackwell Scientific Publications; 1984:79-92.
24. Hadders-Algra M. Early human motor development: from variation to the ability to vary and adapt. Neurosci Biobehav Rev. 2018;90:411-427. 25. Piper M.C., Darrah J. Motor Assessment of the Developing Infant.
Philadelphia, PA: W.B. Saunders Company; 1994.
26. Smith M.G., Liu J.H., Helms K.H., Wilkerson K.L. Racial differ-ences in trends and predictors of infant sleep positioning in South Carolina, 1996–2007. Matern Child Health J. 2012;16:72-82. 27. Nuysink J., Eijsermans M.J., van Haastert I.C., et al. Clinical course
of asymmetric motor performance and deformational plagioceph-aly in very preterm infants. J Pediatr. 2013;163:658-665.
28. International Labour Organization. International Standard Classification of Occupations: Structure, Group Definitions and Correspondence Tables. Geneva, Switzerland: International Labour Office; 2012.
How to cite this article: Straathof EJM, Heineman KR, Hamer EG, Hadders-Algra M. Prevailing head position to one side in early infancy—A population-based study. Acta Paediatr. 2019;00:1–7. https ://doi.org/10.1111/apa.15112
